We are all familiar with touch-activated dispensing devices used, for example, in road side washrooms. These typically include a spring return, hand activated mechanism, which dispenses a predetermined, desirable amount of liquid, as for example hand washing soap, onto the user's palm.
In certain applications, where metallic parts are used in the dispensing mechanisms, the exposure to the liquid can precipitate corrosion unless stainless steel or other non-corrosive type materials are employed. These of course are relatively expensive. Alternately, to avoid the corrosion problem, the dispensing mechanism can be relatively complex, and thus costly, with the components housed in a separate chamber, or external to the liquid container.
In addition, for spring activated mechanisms where the coils of the spring, by design, are immersed in the liquid to be dispersed, a further problem can develop. In these situations the concentration of the liquid solution becomes a consideration.
Solubility is generally a function of the solvent and temperature. As the concentration of a solution increases, up to the limits of solubility for the particular solution, crystallization of the salt in solution can occur. The gap between the coils of the spring is possibly bridged by the crystallizing salt. This will increase the effort necessary to first open the valve; and subsequently slow down the mechanism return causing, perhaps, excessive leakage of the liquid.
It is therefore a primary object of this invention to provide a simple and uncomplicated dispensing valve mechanism which is largely impervious to the corrosive effects of liquid solutions.
It is yet another object of this invention to provide a valve mechanism which will function; notwithstanding that the concentration of the liquid solution is relatively high, thus accommodating a wide spectrum of liquids.
It is still another object of this invention to provide a valve mechanism which will function for a broad range of fluid materials, from dry powders to the more viscous liquids.